Posts Tagged ‘ecosystem’

As previously covered by Solid State Technology CEA-Leti in France has been developing monolithic transistor stacking based on laser re-crystallization of active silicon in upper layers called “CoolCube” (TM). Leading mobile chip supplier Qualcomm has been working with Leti on CoolCube R&D since late 2013, and based on preliminary results have opted to continue collaborating with the goal of building a complete ecosystem that takes the technology from design to fabrication.

“The Qualcomm Technologies and Leti teams have demonstrated the potential of this technology for designing and fabricating high-density and high-performance chips for mobile devices,” said Karim Arabi, vice president of engineering, Qualcomm Technologies, Inc. “We are optimistic that this technology could address some of the technology scaling issues and this is why we are extending our collaboration with Leti.” As part of the collaboration, Qualcomm Technologies and Leti are sharing the technology through flexible, multi-party collaboration programs to accelerate adoption.

Olivier Faynot, micro-electronic component section manager of CEA-Leti, in an exclusive interview with Solid State Technology and SemiMD explained, “Today we have a strong focus on CMOS over CMOS integration, and this is the primary integration that we are pushing. What we see today is the integration of NMOS over PMOS is interesting and suitable for new material incorporation such as III-V and germanium.”

The Table shows that CMOS over CMOS integration has met transistor performance goals with low-temperature processes, such that the top transistors have at least 90% of the performance compared to the bottom. Faynot says that recent results for transistors are meeting specification, while there is still work to be done on inter-tier metal connections. For advanced ICs there is a lot of interconnect routing congestion around the contacts and the metal-1 level, so inter-tier connection (formerly termed the more generic “local interconnect”) levels are needed to route some gates at the bottom level for connection to the top level.

“The main focus now is on the thermal budget for the integration of the inter-tier level,” explained Faynot. “To do this, we are not just working on the processing but also working closely with the designers. For example, depending on the material chosen for the metal inter-tier there will be different limits on the metal link lengths.” Tungsten is relatively more stable than copper, but with higher electrical resistance for inherently lower limits on line lengths. Additional details on such process-design co-dependencies will be disclosed during the 2016 VLSI Technology Symposium, chaired by Raj Jammy.

When the industry decides to integrate III-V and Ge alternate-channel materials in CMOS, the different processing conditions for each should make NMOS over PMOS CoolCube a relatively easy performance extension. “Three-fives and germanium are basically materials with low thermal budgets, so they would be most compatible with CoolCube processing,” reminded Faynot. “To me, this kind of technology would be very interesting for mobile applications, because it would achieve a circuit where the length of the wires would be shortened. We would expect to save in area, and have less of a trade-off between power-consumption and speed.”

“This is a new wave that CoolCube is creating and it has been possible thanks to the interest and support of Qualcomm Technologies, which is pushing the technological development in a good direction and sending a strong signal to the microelectronics community,” said Leti CEO Marie Semeria. “Together, we aim to build a complete ecosystem with foundries, equipment suppliers, and EDA and design houses to assemble all the pieces of the puzzle and move the technology into the product-qualification phase.”

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The increasing demand for wireless data bandwidth and the emergence of LTE and LTE Advanced standards pushes radio-frequency (RF) IC designers to develop devices with higher levels of integrated RF functions, meeting more and more stringent specification levels. The substrates on which those devices are manufactured play a major role in achieving that level of performance.

Everybody’s talking about it, but just what is DFM? According to various EDA company websites, design for manufacturing can be: generation of yield optimized cells; layout compaction; wafer mapping optimization; planarity fill; or, statistical timing among other definitions. Obviously, there is very little consensus. For me, DFM is what makes my job hard: Characterizing it, and developing tools for it, is the most important item on my agenda.

In nanometer designs, the number of single vias, and the number of via transitions with minimal overlap, can contribute significantly to yield loss. Yet doubling every via leads to other yield-related problems and has a huge impact on design size. While there is still concern over of how many vias can be fixed without rerouting and without creating DRC violations, the Calibre via doubling tool can identify via transitions and recommend areas for second via insertion without increasing area.

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